Polymorphic structures of 3-phenyl-1H-1,3-benzodiazol-2(3H)-one

The two polymorphic structures of 3-phenyl-1H-1,3-benzodiazol-2(3H)-one (I and II) exhibit identical bond distances and angles except for the C—N—C—C torsion angle between the benzimidazolone backbone and the phenyl substituent, which has an effect on the crystal packing and supramolecular features. The structure of I contains a stronger C=O⋯H—N hydrogen-bonding interaction and a weaker π–π interaction between adjacent bezimidazolone moieties in comparison to II.


Structural commentary
The title compounds crystallized as colorless needles (I) and blocks (II) in space groups C2/c and Pbca, respectively. The two polymorphic structures exhibit identical bond distances and angles, except for the dihedral angle of the phenyl substituent ( Fig. 1). Both structures retain the planarity of benzimidazolone moiety, as demonstrated by the low r.m.s. deviations of 0.009 and 0.023 Å for I and II, respectively. The C2-N1-C8-C9/C13 torsion angle is 123.03 (14) and À137.18 (12) for I and II, respectively. No additional differences are observed from an analysis of bond distances and angles.

Supramolecular features
Initial investigations of supramolecular features for I and II were carried out using Hirshfeld surface analysis with Crys-talExplorer 21.5 (Spackman et al., 2021). The Hirshfeld surface was mapped over d norm in the ranges À0.6415 to 1.2040 a.u. and À0.5612 to 1.1830 a.u. for I and II, respectively (Figs. 2 and 3). The most intense red spots on the surface for I and II indicate the N3-H3Á Á ÁO1 hydrogen-bonding interactions (Tables 1 and 2), which have R 2 2 (8) graph-set motifs (Bernstein et al., 1995). The shorter DÁ Á ÁA and HÁ Á ÁA distances, and more linear D-HÁ Á ÁA angle reveal that the hydrogen-bonding interaction in I is stronger than that in II. In contrast, the structure of II contains a strongerinteraction between the adjacent benzimidazolone moieties, as defined by the centroidÁ Á Ácentroid distance of 3.3257 (8) Å , while the corresponding distance in I is more elongated at 3.6862 (7) Å .

Figure 1
Molecular structures of (a) I, (b) II, and (c) overlay of I and II with displacement ellipsoids drawn at the 50% probability level.  Most structures feature bimolecular hydrogen-bonding interactions between N-H Á Á Á O C moieties with an R 2 2 (8) graph-set motif, but in ZEDJAX N-H Á Á Á O C hydrogen bonds link the molecules into C(4) chains. The distances between a nitrogen donor and an oxygen acceptor range from 2.79-2.84 Å , comparable to the values for I and II of 2.7786 (14) and 2.8453 (14) Å , respectively.

Refinement
Crystal data, data collection, and refinement statistics are summarized in Table 3. No appreciable disorder was observed for both structures. The hydrogen atoms were optimized using riding models. Synthesis of 3-phenyl-1H-1,3-benzodiazol-2(3H)-one.

Computing details
For both structures, data collection: APEX2 (Bruker, 2012); cell refinement: SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: Olex2 1.3 (Dolomanov et al., 2009); software used to prepare material for publication: Olex2 1.3 (Dolomanov et al., 2009). Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.60223 (5)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.25 e Å −3 Δρ min = −0.37 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.